Robert, I think it’s your radiator. I’ve had lots of guys try units from “they build radiators for race cars” guys, and every single one runs hot. When they go to the 1989 Aerostar rear heater core (OEM only, aftermarket ones won’t work. The OEM unit is all aluminum, and dip soldered. You can JB weld on an air bleed screw fitting), their water temps drop back down to the 145-155 range. The Ford part number is E99z-18476-B. These little radiators are well designed, durable, and reject a ton of heat. Topeka was in the high 90’s and my water temp max was 165 with the D-C EBP 15 electric pump, with no thermostat. All the karts I’ve built are running the same setup, and getting about the same temps. BTW, below 80 deg I do still run the IAME inline thermostat with two extra 3/32″ bypass holes in it.